Altitude time-dial.



P.J.DIOK. ALTITUDE TIME DIAL. APPLICATION FILED DEO.17,190T

Patented N0v.22, 1910.

l/WE/VTOR {HOURS AFTER THE NORRIS PETERS ca. wAsHmnmN n c FREDERICK J. DICK, OF POINT LOMA, CALIFORNIA, ASSIGNOR TO KATHERINE TING-LEY, OF POINT LOIVIA, CALIFORNIA.

ALTITUDE TIME-DIAL.

To all whom it may concern:

Be it known that I, FREDERICK J. DICK, a subject of His Majesty the King of Great Britain, residing at Point Loma, in the county of San Diego and State of Califor nia, have invented certain new and useful Improvements in Altitude Time-Dials, of which the following is a specification.

The objects of my invention are to provide a simple means of ascertaining the standard or the local mean time by day or night at any place within wide limits of latitude independently of any mechanical timepiece, and of any ephemeris; to provide an inexpensive instrument, namely an altitudetime-dial, by means of which timepieces can be corrected regulated or rated with suffioient accuracy for most purposes, the dial being when desired capable of easy transportation and even of being carried with facility in the pocket; and to stimulate, especially among the young, an interest in the uses of elementary practical astronomy.

My invention consists of two plates, hereinafter called the declination-plate and the hour-plate, adj ustably connected so that their relative positions can be changed for various degrees of latitude; one furnished with means for adjustably moving, to positions corresponding to various declinations of celestial bodies, the point of oscillation of a plumb-line whose point of attachment to this altitude-time-dial is non-coincident with the variable point of oscillation, the point of attachment being suitably guided to adjustably move along a circular arc; and the other having suitable hour-lines delineated thereon, together with other subsidiary lines subdividing each hour into convenient intervals, which subsidiary lines are hereinafter included in the expression hour-lines; the hour-plate furnished with means for determining among these lines the points proper for reference at the same various degrees of latitude; and the hour-plate and plumb-line furnished with means for suitably referring an indicating-point fixed upon the plumb-line to the aforesaid points on the hour-lines.

I attain these improvements by the general arrangements illustrated in the accompanying drawing, in which- Figure 1 is a front view of the altitudetime-dial, and Fig. 2 is a front View of a Specification of Letters Patent.

Application filed December 17, 1907.

Patented Nov. 22, 1910.

Serial No. 406,921.

radial arm, interposed between the hour and declination plates, which carries the point of attachment of the plumb-line to the dial.

Similar letters refer to similar parts in the two figures.

B (Fig. 1) represents the declinationplate, which is connected to the hour-plate D. I may connect these in any manner admitting of relative angular movement according to the indications of a suitable latitude'scale on either plate, shown on the hour-plate at C, but in my preferred construction I use a pivoted connection, shown at E. a This latitude-scale C, on the hourplate, is divided and marked so that when the lower edge of the declination-plate is brought to any given degree of latitude (shown at 10 in Fig. 1) the line (shown by the dotted line from O to the scale S), joining the zero-declinationpoint in the middle of the declination-scale S, with the center of the pivot at E, makes an acute angle with the top edge of the hour-plate, X, of that number of degrees (40 in Fig. 1). The declination-plate B being thus set, with regard to the hour-plate D, at the proper angle corresponding to the latitude,

these plates or cards will remain frictionally in this relative position (or they may have the aid of an ordinary paper-clip applied at the margins). The efi'ect of this arrangement in cooperation with the otherarrangements is explained hereinafter.

I may use various means for causing the point of attachment of the plumb-line to the dial to adjustably move along a circular arc, but in my preferred construction I use a radial arm or plate R (Figs. 1 and 2) interposed between the hour and declination plates. This arm adjustably rotates on the same pivot at E.

I may use various means for controlling the point of oscillation of the plumb-line KK (Fig. 1) to adjustably move along the line A (Fig. 1), but my preferred construo tion is as follows.

The plumb-line KK is attached to a point L (Fig. 2) at the back of the radial arm R. Thence it passes, through the slit V (Fig. 2) cut in the radial arm, and next through the slit A (Fig. 1) cut in the declination-plate B, to the front of the said plate as shown by the line KK. Thus the point Q, where the lines of the two slits intersect, and where the plumb-line passes through to the front of the declination-plate, is at variable distances from the center of the pivot E, when the radial arm R is moved to different degrees of declination; and this point Q is thus a variable point of oscillation for the plumb-line KK.

S represents the declination-scale delineated upon the declination-plate. This scale is required for bringing the point of oscillation Q, to the position corresponding to the declination of a celestial body. This is effected by first pulling the plumb-line at Q through to the back of the dial a little, so as to allow of free movement of the radial arm It; next bringing the mark shown in middle of extremity of radial arm P to the particular degree of declination required, whether north or south; finally pulling the plumbline through to the front again, when the point Q, where the plumb-line emerges from the slit A, (which thus becomes the point of oscillation of the plumb-line), will lie in a straight line with the given declination-degree (7 1, north in Fig. 1) and the center of the pivot at E. The center of the circular scale S is the center of the pivot at E.

Part of the plumb-line KK consists of a double-eyed rod T, having small needle-eyes at either end, the flexible parts of the plumbline being connected thereto at these small eyes, one at the upper, and the other at the lower end J, of the rod T. These eyes are too small to be visible in the drawing. The point J is the indicating-point on the plumb-line hereinbefore referred to. The distance of this point, measured along the plumb-line, from the point L, is identical with the distance of the point L from the center of the pivot at E.

The method of delineating the hour-lines is as follows. The upper and lower edges, X and P, of the hour-plate are strictly parallel. A line through the center of the pivot at E, perpendicular to these edges must contain the XII point of the hour-lines, and this XII point having been marked in a convenient position on that perpendicular may then be regarded as the origin of coordinates parallel and perpendicular to the edges X and P. This XII point, on Fig. l, is the point marked XII at the left extremity of the line G.

In order to apprehend what follows, it may be found desirable to refer to the math ematical principles underlying altitude dialin which are clearly set forth in the article ialing, section Portable dial, in the Encyolopoeclz'a Britannica, Vol. vii, p. 161, et seq. 7

If r represent-s the distance of the center of the pivot at E from the zero-declination point 0 on the line or slit A, p the hour-angle fromthe meridian, and lo the latitude of the place of observation on the earths surface, then the abscissa a? (parallel to the edges X and P) of any hour-point (or subdivision) for any latitude is- 66:1 cos. 7:; (1cos. p)

The article referred to contains the demonstration of the truth of this proposition. The ordinates through such points being then drawn, they will intersect any inclined line drawn from the origin of coordinates, namely, from the XII point. The lower latitudescale H consists of such a series of inclined lines drawn from the XII point, one of which, G (representing the latitude thread hereinafter referred to), is shown in Fig. 1 extending the whole way from the XII point to thedivision of the scale I-I marked as for the 40th degree of latitude. Upon this line G, therefore, may be plotted the hour-division points corresponding to that latitude. Thus r in Fig. 1 being 4 inches, and 7) being say hours (from the meridian) 829 the abscissa of the hour point .on the line G will be- 00:4: cos. e0 (1-cos. 821 2 .66% inches,

which is the distance from the XII point of the vertical dotted ordinate shown passing through the 5.30 p. in. (and 6.30 a. point on the line G. In the same manner the abscissa; for other hour-angles at the latitude 40 are plotted on the line G. And in the same manner the hour-division points are found for the other degrees of latitude, and the curves for each hour-angle, between the latitude limits determined upon, are then drawn in, as shown by the curved lines F. I may use various means for indicating on hour-lines the particular hour-positions corresponding to a given latitude, but in my preferred construction I use an adjustable elastic thread G which passes through the declination-plate at the XII point and, extending across the dial-face, returns to the same XII point at the back. It has a loop or ring N for convenience in shifting it to the degree on the scale I-I corresponding to the latitude of the place of observation. On the hour-plate are also delineated a number of parallel lines UU, perpendicular to the edges X and P, but not visibly intersecting the hour-lines F.

Any convenient range of latitude may be adopted for the instrument. That shown in Fig. 1 is available throughout the entire area of the United States, namely, from 25 N. to 50 N. lat.

The-line N, drawn parallel to the edges X and P, with its relative hinged gnomon, shown on Fig. 1, is, as is usual on carddials merely for convenience in directing the instrument to the sun, when that happens to be the celestial body used.

It is only necessary to explain that when the upper or lower edges, X or P, or the line N, are pointed at a celestial body-after the instrument has been set for that bodys declination and also for the latitude of the place of observation-the plumb-line is steadied and then pressed with the finger against the lower part of the hour-plate. The rod T is now pressed against the hourplate with the other hand, and the lower part of the plumb-line released and brought parallel to the guide-lines, UU, as shown by the dotted line on Fig. 1 running down from the indicating-point J. The apparent time is then read off at the point where the plumb line now crosses the latitude thread G.

In Fig. l the instrument is shown as set for latitude N, the celestial body used having a supposed declination of 74 N. The apparent time indicated in Fig. 1 is 6.30 a. m., or 5.30 p. m.

hat I claim as my invention and desire to secure by Letters Patent is- 1. In an altitude-time-dial the combination of two plates pivotally connected to admit of adjustable movement suitably corresponding to various latitudes, a plumb-line attached to a radial bar or plate, and means for introducing, between the point of attachment of the plumb-line to the radial bar or plate and an indicating-point on the plumb-line, a point of oscillation on said plumb-line at adjustably varying distances from the point of attachment, substantially as described.

2. In an altitude-time-dial the combination of two plates pivotally connected, and

a pivotally connected adjustable radial bar or plate, to which a plumb-line is attached, and means for causing a variable point of oscillation on said plumb-line to adjustably coincide with a particular series of points on one of the plates suitably corresponding to various declinations of celestial bodies, substantially as described.

3. In an altitude-time-dial the combination of two plates pivotally connected to admit of adjustable movement suitably corresponding to various latitudes, a plumb line attached to a pivotally connected radial bar or plate, and means for suitably referring an indicating-point, permanently fixed on the plumb-line, to several particular series of indicated points on one of the plates suitably corresponding to various hour-angles at the same various latitudes, substantially as described.

4. In an altitude-time-dial the combination of two plates pivotally connected to admit of adjustable movement suitably corresponding to various latitudes, a radial bar or plate, a plumb-line attached thereto, and an adjustable elastic thread for indicating on certain hour-lines suitably delineated on one of the plates the particular series oi points proper for reference at the same various latitudes, substantially as described.

In testimony whereof I aifix my signature in presence of two witnesses.

FRED. J. DICK.

Witnesses:

J. FRANK KNOOHE, C. THURSTON. 

